Electronic locking circuit



May 4, 1948. A. E. CANFORA ELECTRONIC LOCKING CIRCUIT Filed June 28, 1945 OUTPUT I N V E N TO R Aer/we f. Owl/om ATTORN EY Patented May 4, 1948 ELECTRONIC LOCKING cmourr Arthur E. Canfora, Brooklyn, N. Y., assignor to Radio Corporation of America, a corporation of Delaware Application June 28, 1945, Serial No. 601,957

Claims. 1

This invention relates to locking circuits. More particularly, the invention relates to a device having the characteristics of an aperiodic trigger circuit such as is commonly used in code signal keying and electronic switching.

It is an object of my invention to provide a locking circuit which shall be more stable in operation than those heretofore used where it was necessary to obtain a substantially exact equation between the triggering potentials applied reciprocally to the input circuits of two discharge tubes.

It is another object of my invention to provide a dual triode locking circuit of the type which makes use of a gaseous glow tube for performing the function of interaction between the two triodes of the locking circuit.

A feature of my invention consists in the substitution of a neon lamp or the equivalent for a resistor in one of the cross-connections between the anode of one tube and the control grid of a second tube.

In the conventional locking circuit two discharge tubes are provided having interconnected control circuits such that the anode of each tube supplies triggering potential to the control grid of the other tube. Such a locking circuit must be designed, built and operated within close tolerances, particularly as to the values of the voltage divider elements which extend from the anode of each tube to the negative terminal of a biasing source. It is also necessary to select with great care the proper tappin point along these voltage dividers for supplying control potentials to each grid. Then again, the supply voltages must be maintained within a close range of the theoretically calculated value in order to avoid improper operation of the circuit.

When locking circuits are used in pulse counters of the binary type, it was sometimes found advantageous to employ neon lamps merely as an accessory to the conventional locking circuit for the purpose of indicating the number of counts registered. Such lamps did not, however, contribute in any way to the dependability of the locking circuit action.

According to my invention, a gaseous glow tube or neon lamp is introduced into the circuit for the purpose of contributing materially to the stabilizing of the locking circuit action, in addition to acting as an indicator. The glow tube is a gaseous diode.

My invention will now be described in more detail reference being made to the accompanying drawing the sole figure of which represents diagrammatically a preferred circuit arrange ment.

The drawing shows two triode discharge tubes I and 2. A source of operating potential 3 is shown having four sections E1, E2, E3 and E4 respectively. If desired the source 3 may have connected across its terminals a voltage divider from which taps may be taken off for supplying the necessary potentials of difierent values to different parts of the circuit. The cathode 4 in tube l is connected to the junction between sections E2 and E3 of the source 3. The anode 5 is connected through a resistor'fi to the most positive terminal of the source 3. The control grid I is connected through a resistor 8 to ground and to the junction between sections .El and E2 of the source 3, i

Triode tube 2 has its cathode 9 connected to the junction between sections E3 and E4 of the source 3. The anode I0 is connected to ground through the resistor 8. The connection between the anode l0 and the control grid 1 in tube I has a negligible resistance value. A voltage divider comprising three sections I I, I2 and; I3 is connected between ground and the most negative terminal of the source 3. The junction between voltage divider sections l2 and I3 is connected to the control grid I 4 in tube 2. The junction between voltage divider sections II and I 2 is connected through a gaseous glow tube l5 to the anode 5 in tube An input circuit having terminals [6 is shown connected between the control grid land ground. 'An output circuit I1 is shown having one terminal connected to the anode 5 and the other terminal grounded. Both the input and output cir cuits may be differently connected, however, in various ways, as will be understood by those skilled in the art. The choice ofjpositions for taking oi the output is largely determined by the wanted polarity of the signals.

The operation of the circuit will now be "de-v scribed, Assume that tube I has been rendered conductive by a positive pulse applied across the input terminals l6. The reduced anode .potential that tube 2 will be biased to cut-01f under these conditions.

It should be noticed that'the potent al or the" Let it now be assumed that a negative signal pulse is applied across the input terminals it,

thereby biasing the grid I in tube I so far negative as to render tube 1 non-conductive. Then the anode potential in this tube is raised sufficiently high to cause the neon tube [-5 to ignite; The junction between voltage divider. sections iiand I! now receives a potential boost from the most positive terminal of source 3. In other. words, a circuit is established from the most negative terminal of the source 3 through voltage divider sections l3 and i2, thence through the neon tube l5 and through resistor 6 to the most positive tor-- mlnal of source 3. Under this condition the grid 1-4 in tube 2 ispositively biased and causes this tube to be conductive. Current now flows from the cathode 9 through the tube,and through resistor 8 to ground. Thisbiases the grid '1 negatively-andproduces'a locking action. such that tube 1 becomes non-conductive. By proper-1y proportioning the resistor values .it is possible to obtaina very considerable vcltageiswing on the gridsand J 4., aslbetween positive and negative values with respect-to t'heircathodes. Th-us: the circuit is rendered less critical in respect-to the values of the input potentials; and, furthermore, the stability ofaction is assured V Thesinterdependence of action of each tube upon the other involves a control voltageswing the range of. which is extended by'the use of the neon lamp l5. 'Thelamp produces a self-switching-action toopen and closeits: circuit between the anode 5 and the junctionbetween voltag-e divider sections H and 1.2.: This junction point. is thus fioodedwith highpositive potential-atone time, that" is,=during the conductive state of. the neon tubel5; .yetwhen this tube is extinguished the voltage divider is entirely isolated vfrom the action ofztube L, r i

The stability of action ot-tub e l depends also,

to some extent, upon the substantially negligible resistance value of the connection between its grid 1 and the anode I0 in tube 2. Tube 4 is always biased to cut-ofi while tube 2 remains conductive, thatlis, until a su'fiiciently positive. impulseis appliedacross the .inputterminals l'ii. It should be observed, however, that the. potential of the anode.

vacuum dischargetubes each having a cathode.

an. anode and a control grid, a direct current sourcehaving suitable connections to'diirerent parts of said. locking circuit whereby said tubes are. activatedlone at a time, said connections ineluding (l) a resistor in circuit between the anode ofone tube and the most positive terminal of said'sou'rce, (2) a connection of. neg-ligibleimpedance between the control grid of'said one. tube and the anode of. the other tube, (3) a resistor in circuit between said connection of negligible impedance and a grounded point intermediate the terminals of said source, (4) a voltage divider having three sections serially connected between ground and the most negative terminal of said source, the negative end of the middle section being connected to the control grid of said other tube, (5) a direct connection between the oathode of said one tube and an intermediate terminal of said source which is more negative than ground, ('6) a direct connection between the cathode of said other tube and an intermediate terminal of said-source which maintains this cathode more negative than the cathode of said one tube, and a, gaseous diode connected between the anode of said one tube and the positive end of the middle section of said voltage divider.

2. An electronic relay comprising two vacuum discharge devices each having a cathode, an anode and a control grid, 2. negligibly low resistance connection between the control grid of one device and the anode of the other device, a resistor connecting said connection to a point of reference potential such as ground, a direct current source having sections which supply a positive potential with respect to ground and three different potentials C1, C2 and C3 which are progressively more and more negative with respect to ground, a re sistive connection between the anode of said one device and the positive terminal of said source, a direct connection from the cathode of said one device to a source terminal which supplies potential G1, a direct connection from the cathode of said other device to a source terminal which supplies potential C2, a voltage divider having three sections connected between ground and a source terminal which supplies potential C3, the middle one of said voltage divider sections being connected at its negative end to the control grid in said other device, and a gaseous diode connected between .the anode of said one device and the positive end of the middle one of said voltage divider sections.

3. 'A trigger circuit comprising two vacuum dischargetubes each having a cathode, an anode and a control grid, direct current source for maintaining the cathode of thefirst tube. at a more positive .potential than the cathode of the second tube, a resistive connection from the positive terminal of said source to the anode of the first tube, a direct connection between the. control grid of the first tube and the anode of the second tube, a resistor connecting the grid of the first tube to a point of reference potential on said source which point is more negative than the positive terminal of said source and more positive than the cathode of the first tube, means including a gaseous diode in circuit between the anode of the first tube and the control grid of the second tube for providing a trigger control of the second tube by the first tube, means for subjecting the control grid of the first tube. to an externally derived signal control potential such as to render that tube conductive, and a voltage divider having three sections across which a potential drop is normally produced by said direct current source, one extremity of said voltage divider being maintained at a positive potential with respect to the cathode of the first tube, the other voltage divider extremity being maintained at a negative potential with. respect to the cathode of the second tube, and the middle section of said voltage divider forming a connection between said gaseous diode and the controlgrid in said second tube.

4. In a circuit arrangement for producing an .5 aperiodic rectangular wave in response to the application of discrete control pulses from an external source of signals, the combination of two electron discharge devices each having an anode, a cathode and a control grid in a locking circuit so constructed and arranged that it has two positions of stability in either of which the locking circuit rests until tripped therefrom by control pulses of suitable variable absolute magnitude, said arrangement comprising means for applying said control pulses to the control grid of one device, potential sources coupled to the electrodes of said devices with the potential drop through the space path of the said one device in a more positive range than that through the space path of the other of said devices, output terminals for said locking devices, and a gaseous diode discharge tube in circuit between the anode of the one said device and the input circuit of the other said device to extend the range through which the magnitude of said control potentials may be varied above and below a critical range at which said tripping action takes place.

5. A locking circuit so constructed and arranged that it has two positions of stability in either of which positions the locking circuit rests until tripped therefrom by a control pulse of suitable polarity, said locking circuit comprising two electron discharge tubes each having an anode,

of reversible polarity coupled to the control grid and cathode of one tube, a direct current source having a plurality of intermediate taps in addition to its positive and negative terminals, said taps and terminals having individual connections to the anodes and cathodes of the tubes so that the voltage drop through one tube when it is conductive is in a more positive range than the voltage drop through the other tube when it is conductive, means including a gaseous diode tube in a lead between the anode of one tube and grid of the other tube for enabling a high anode potential in said one tube to drive the control grid in the other tube more positive, and a direct low impedance connection between the anode of said other tube and the control grid in said one tube whereby said one tube is rendered conductive when the other tube is biased to out-off.

ARTHUR E. CANFORA.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

